From this work, there is clearly significant benefit to using advanced processes for oil extraction such as HTL or microwave enhanced processing.Compared to other parts of the extraction process, such as energy used for drying, the use of a microwave has been shown to be economically viable.
Efficient treatment of wastewaters is essential as wastewaters contain environmentally harmful substances, such as biodegradable organics, nutrients, metals and pathogens.
However, many of the traditional wastewater treatment processes are energy- or resource-intensive.
Powdered Chlorella vulgaris biomass was treated with hydrothermal treatment (Hydrothermal Liquefaction, HTL) in a reactor between 40-350 o C at holding times of 30 and 60 min.
The vapour pressure developed in the reactor were calculated with the Clausics-Clapeyron equation and with some realistic assumptions.
Microalgae can efficiently remove nitrogen and phosphorus from wastewaters.
Apart from enhancing wastewater treatment efficiency, the microalgae-based treatment systems were developed to promote microalgal growth as the produced microalgal biomass can be used in the production of e.g. Various kinds of wastewaters are produced in large quantities due to urbanization, industrialization and population growth.Aqueous phase reforming (APR) of powdered Chlorella vulgaris biomass was done at the University of Zaragoza, Spain to produce hydrogen with or without Ni catalyst with two pressure 30 or 35 bars at 227 o C.The maximum H2 yield was 0.427 x 10-3 and 0.542 x 10-3 moles of H2 per 3 g of dry algal biomass, with Ni as catalyst at both pressure conditions.These advantages should scale with production volumes.HTL and APR offer similar advantages for processing wet feedstock’s, eliminating drying requirements altogether.This thesis investigates and compares different oil extraction methods and tries to fill the research gaps in the oil extraction processing, for example, utilising new techniques such as ultrasonic or microwave assisted solvent extraction.A detailed energy analysis for the extraction processes was conducted for each method to investigate the process feasibility to produce biodiesel more economically.The bio-oil content yield was found higher at 350 o C with 30 as compared to 60 min holding times and the GC-MS analysis showed the presence of fatty acids (C14-C18).The aqueous phase contained TOC, TN and TP, which are useful nutrients for microalgae cultivation.The de-oiled cake and in-situ cake were torrefied (slow pyrolysis) to convert the residue into a high energy density solid bio-char, which can be used as a feedstock to produce heat energy.Microalgae can be used as a source of biofuel and food supplements, however, their exploitation is lacking due to various bottlenecks including realistic processing options at scale.